Method for forming cast articles from alloys of lead with calcium and metals of similar properties



I potassium,

Patented Feb. 10, 1942 V r 2,272,181] ME'rnon roar'omvmvd CAST ARTICLES -FR.0M ALLOYS F LEAD wrrn'cALorUM AND METALS or snmmn PROPERTIES George MJBouton, Lynbrook, Nflf vand Earle E.

Schumacher, Bell Telephone Maplewood; N. 1.;

Laboratories, Incorporated, New

assignors to York, N. Y., a corporation of.New York a No Drawing;

Y This invention relates generally to the prevention' of the oxidation of" the surface of molten Application September 22; 1939, Serial No. 296,062. i x

j 2 Claims. (Cl. 22-9214 foamin Alloys lead-tin do not exhibit this foaming tendency.

lead-calcium alloys-and molten alloys of lead containing calciumin connection with casting operations wherein. the molten lead has heretofore been exposed to' the open atmosphere'and more specifically tothe preventionof' the oxidation of the heated surface of such alloysduring the pouring and casting. operation.

Storage battery grids have'long been made of pure lead; recent proposals have been made to make such grids of lead-calcium alloy :containing a substantial amount, of calcium, usually somewhat above. 0,138 percent calcium and the balance pure lead; Battery vgrids arepoured into individual-molds and a seriousdifficulty has been encountered in that the expected desirableresult, namely, a more durableand longer lived.-

grid, of using the calciumicontaining alloy has not been realized. This situation? has been In accordance with the present invention as applied to the casting of battery grids carbon dioxide is introduced into and over the molds during casting.

Experiments have shown that with the use of carbon dioxide no dross is visible upon the surface of the alloy and the'surface'of V the lead-calcium alloy has a' bright mirror-like appearance completely free from the dull gray appearance of castings made in air and therefore badly oxidized,

The principles'of to thegi inelting of lead-calcium alloys and the greatly improved 'bylthe use of-jcarbon: dioxide for flooding 'the' castinghtable and the molds with C02 before and-duringlthe casting operation.

It has generally 4 been supposed I that "carbon dioxide is an oxidizing agent for-calcium at the melting point oi'i lead or} 'above;- in its specific aspect this invention; is therefore based upon the discovery that the'co'nta'ct ofcarbon: dioxide with the hot:lead=calciunralloyprevents oxidation not only ofthe leadibut' ofthegcalcium'gi It acts as a protectingagent-andproduces a bright mirrorlike surface upon the' exposed lead-calciumalloy.

In .its general; aspect .thisiinvention is based on the discovery that carbomdioxideyact's a preventative oxidation. during casting of lead-calcium alldys and allo ys' of lead with other alkali oralkali earthmetals; speciilcallyflitliium, strontium. There appear to g de from,using-carbor idio eas"a me e non stain-st oxidatio fd n i'the pouifinkf-and casting of pureleadgorfiailoys ch as @leadantimonygleadz-fin; Or or lead with I combinations ofc dfmium ktimf nd ntimonyfi n md nwd l ii m'ris 't rez a tendency ww d m hiasjm a in i us of carbon dioxide invention prevents or frotliingj or no practise beneficial eflects v casting of articles therefrom,; In melting 1eadcalciumalloy 8. cover of C02" is-- kept over the,

surface of the molten metal andin pouring the material into molds, for example; to Lp'roduce storage battery grids; the space in and around the mold may be filled with CO2. In the production of such grids or other articles a calcium content of 008 or somewhat higher may be used.

s It has beenwfound that 'pr cent concentration of CO: with resultantacom'plete displaceme'nt'of all the air is not necessary for efiective results; a substantial displacement ofthe air by CO2 is beneflciah In practice even appreciable admixtures of air through convection currents or-other eifccts do not alter the eifectiveness of the carbon dioxide. v

What is claimed is:

1. Method of forming cast articles such as I storage battery gn'ds from a molten alloy of lead "withcalcium which comprises maintaining an atmosphere of carbon dioxide over the molten alloy in'the kettle, around the pouring spoutor ladle and m the cavities of the mold during the fllling thereof.

i 2. The method of forming. cast articles such a :.battery-grids, from molten lead alloy'contain in'g one or more'pf the constituents calcium, lithium, barium, strontium, potassium and sodium whichcomprlses maintaining a shield of dioxide over and around the alloy during the pouring and casting operations.

GEORGE u. a EAR-LE E. SCHUMACHER.

of lead, lead-antimony and the invention are applicable 

